The adult human brain weighs about 3 pounds (1,300-1,400 g).
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Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
There are times when you're walking that the pressure on your feet exceeds your body weight, and when you're running, it can be three or four times your weight.
62
The largest cell in the human body is the female egg and the smallest is the male sperm.
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Your heart will pump about 212 million liters in its lifetime.
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Every year your body replaces 98% of your atoms.
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When you take a step, you are using up to 200 muscles.
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An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
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